<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div>
    <a href="http://www.sogou.com">
        <span id="seconds">3</span>秒后系统会自动跳转，也可单击此链接跳转
    </a>
</div>
<script>
      function timing(secs, url) {
        var seconds = document.getElementById('seconds');
        seconds.innerHTML = secs--;
        if (secs > 0) {
          setTimeout('timing(' + secs + ', \'' + url + '\')', 1000);
        } else {
          location.href = url;
        }
      };
      timing(8, 'http://www.sogou.com');
    </script>
</body>
</html>